ozij wrote:I don't understand why the machine is setup to let your IPAP go as low as 10.
It seems to me the machine is given far too much headway, starting at anything below an EPAP of 11 or even 12 looks to me like asking for trouble. The machine simply can't resopnd to your apneas at tha pressure.
For the benefit of
anyone who did honestly not understand the above statement:
Setting up the EPAP at 8 and letting the PS go down to 2 means there may be times when IPAP is only 10. Given the data I see, that is too low in my opinion, and I don't undrstand why
the machine was set up like that by whoever set it up.
An EPAP of 11 or 12 would of course have kept the IPAP at a minimum of 14. Simple reasoning and mathematics.
O.
You NEED to first understand how the machine functions before you can make sense of that statement.
That 2 cm PS you are talking about is hard-coded in the machines firmware, you are NOT going to change it. So there is no "letting PS go down to 2" it is just there as Respironics feels a minimum of 2 cm PS is always needed in the Auto mode.
You CAN adjust the "Maximum" PS which ranges from 3cm to 8cm, but you cannot change the "minimum" value.
There is also NO IPAP "Minimum" on this machine. That Minimum is controlled by Minimum EPAP setting and the built-in 2 cm Pressure Support. SO if you set EPAP=8 then IPAP Minimum is automatically set 2 cm higher at 10 cm, if you set
EPAP=10, iPAP will be at 12 cm and so on.
That built-in 2 cm PS is like a tennis ball between IPAP and EPAP pressure. It will never get closer than 2 cm. The settable Maximum is a like a string or tether between the two pressures, it can go farther apart based upon the PS "Max" setting used which has a range of 3 to 8 cm.
The best way to describe it is the hard coded PS is a tennis ball between the two pressures, the one you set with a range of 3 to 8 is a string. As events dictate those pressures will move independently of each other until it either runs into the tennis ball or reaches the end of that string.
To understand PS and how it works it is NOT just the difference between IPAP and EPAP, it is like an invisible "band" of pressure in the center of Inhale and Exhale, the farther apart you allow PS the wider or taller that band gets.
While they are both called PS for Pressure Support, there is a Minimum and a Maximum. The Minimum is hard-coded, the Maximum you can change and picks up from the hard coded value at 3 cm and goes to 8 cm Maximum. These are rules the machine follows while in "Auto" mode.
The thing to do is use EPAP Minimum setting to titrate and eliminate OA. Once that is acceptable, you manipulate PS setting (going from 3 to in which the algorithm will automatically take IPAP up in the presence of events that drive up IPAP pressure which is mainly HI, VS, and FL. Increasing PS Max setting allows IPAP to separate higher from EPAP pressure without increasing it until it reaches the end of that proverbial "string" where it then begins pulling up EPAP higher.
Now if all the events are mainly OA as seen in BigEd's case, those apnea will trigger EPAP to increase, when that happens EPAP runs into that hard coded 2 cm PS and begins pushing up IPAP. It is shown right in the reports, count the pressure tics, when you see 2 tic separation between IPAP and EPAP "working" pressure (not the range) that says EPAP is pushing up IPAP based upon current SDB event.
When you see 3 cm or greater separation then that means IPAP is responding independently and if EPAP rises it is because it reached the end of the proverbial string of the settable PS setting and is now pulling up EPAP. This falls then under the little hammer big hammer theory SAG described years ago.
IF you want to allow greater separation or greater PS you increase the PS setting from default=3 to 4 or higher all the way up to 8. 8 is the Maximum that machine will allow. The only reason you want to allow a greater PS is to keep the EPAP pressure down independently. For example if the report shows that SDB events are all HI you might want to allow IPAP to go higher without pulling up EPAP. But this can work against you on the down side. As events subside that "string" works the opposite, as EPAP falls for absence of events it has to reach that PS setting before it pulls IPAP down. If PS is at 4 it will pull that IPAP pressure down before it will at a setting of 8.
It is very important on this machine to allow it a wide range of operation. The higher the PS setting you use the wider that range has to be. That "range" is determined by the EPAP Minimum setting and the IPAP Maximum setting in addition to any PS setting you use.
For example, it does NO good setting EPAP at 12 and IPAP at 16 and using a PS=8 it will NEVER be used as there isn't 8 cm separation allowed in that range.
Eliminate OA first with EPAP setting, then observe reports, if HI persist extend the PS setting. Goal is keeping EPAP at a level where it just eliminates the OA then allow IPAP to run up to clean up the rest. If you are still seeing HI then shortening the PS setting will force the machine to bring out the big hammer and increase EPAP sooner (not faster, sooner).
Those settings are not a set it here and hope it works, you observe OA and increase the one designed to get the job done. Use the legend at the bottom of the Daily report to determine which pressure needs to change to eliminate the event. Notice HI is on IPAP and OA is on EPAP? Adjust the pressure for the event you want to prevent. EPAP being the big hammer eventually takes care of all events just like CPAP pressure does.
